feat: 🎸 scan and scanN now work like map

scap applies jth init value and jth callback to jth output

BREAKING CHANGE: 🧨 scan and scanN changed to behavior consistent with map

Author: dmitriz

index.js

@@ -284,7 +284,7 @@ exports.scan = (...initStates) => (...reducers) => exports.map(...reducers.map(
 ))
 
 // simplified scan dropping the seed
-const scanS = (...args) => exports.scan(...args, undefined)
+const scanS = (...args) => exports.scan()(...args)
 
 
 /**

test/scan.test.js

@@ -1,5 +1,5 @@
 const test = require('./config')
-const { map, scan, scanS } = require('..')
+const { update, map, scan, scanS } = require('..')
 
 test('scan over single callback output', t => {
 	const reducer = (acc, x) => acc + x
@@ -13,65 +13,62 @@ test('scan over single callback preserves outputs from other callbacks', t => {
 	t.plan(2)
 	scan(10)(reducer)(cpsFun)(t.cis(10+42),t.cis(5))
 })
-// test('scan ignores undefined/null args', t => {
-// 	const r = (acc, x) => acc + x
-// 	const cpsFun = (c1,c2) => {c1(42)}
-// 	const cpsFun1 = (c1,c2) => {c2(42)}
-// 	const cpsFun2 = (c1,c2) => {c1(10+11);c2(11)}
-	// t.plan(5)
-	// map(null, notCalled)(cpsFun)(t.cis(42))
-	// scan(10)(null, r)(cpsFun)(t.cis(42))
-	// scan(undefined, r, 10)(cpsFun)(t.cis(42))
-	// scan(undefined, r, 10)(cpsFun1)(t.cis(10+42))
-	// scan(undefined, r, 10)(cpsFun2)(t.cis(10+11))
-// })
-// test('scan over single repeated callback output', t => {
-// 	let called = false
-// 	const reducer = (acc, x) => acc + x
-// 	const cpsFun = cb => { cb(2); cb(8) }
-// 	const newCps = scan(reducer, 10)(cpsFun)
-// 	t.plan(2)
-// 	newCps(res => {
-// 		t.cis(called ? 10+2+8 : 10+2)(res)
-// 		called = true
-// 	})	
-// })
-// test('scan over outputs from 2 callbacks', t => {
-// 	const r = (acc, x) => acc + x
-// 	const cpsFun = (cb1, cb2) => {cb1(2); cb2(3)}
-// 	const newCps = scan(r, r, 10)(cpsFun)
-// 	t.plan(2)
-// 	let count = 0
-// 	newCps(res => t.cis(count++ === 0 ? 10+2 : 10+2+3)(res))	
-// })
-// test('scan with multiple functions applies each to the same seed', t=>{
-// 	const r1=(acc, x) => acc + x, r2=(acc, x) => acc * x
-// 	const cpsFun = (cb1, cb2) => {cb1(2); cb2(3)}
-// 	const cpsFun1 = (cb1, cb2) => {cb2(2); cb1(3)}
-// 	const newCps = scan(r1, r2, 10)(cpsFun)
-// 	const newCps1 = scan(r1, r2, 10)(cpsFun1)
-// 	t.plan(4)
-// 	let count = 0
-// 	newCps(res => t.cis(count++ === 0 ? 10+2 : (10+2)*3)(res))
-// 	count = 0
-// 	newCps1(res => t.cis(count++ === 0 ? 10*2 : (10*2)+3)(res))
-// })
+test('scan ignores undefined/null args', t => {
+	const r = (acc, x) => acc + x
+	const cpsFun = (c1,c2) => {c1(42)}
+	const cpsFun1 = (c1,c2) => {c2(42)}
+	const cpsFun2 = (c1,c2) => {c1(2);c2(11)}
+	t.plan(5)
+	scan(10)(null, r)(cpsFun)(t.cis(42))
+	scan(10)(undefined, r)(cpsFun)(t.cis(42))
+	scan(null,10)(undefined, r)(cpsFun1)(null,t.cis(10+42))
+	scan(null,10)(undefined, r)(cpsFun2)(t.cis(2),t.cis(10+11))
+})
+test('scan over single repeated callback output', t => {
+	let called = false
+	const reducer = (acc, x) => acc + x
+	const cpsFun = cb => { cb(2); cb(8) }
+	const newCps = scan(10)(reducer)(cpsFun)
+	t.plan(2)
+	newCps(res => {
+		t.cis(called ? 10+2+8 : 10+2)(res)
+		called = true
+	})	
+})
+test('scan over outputs from 2 callbacks', t => {
+	const r = (acc, x) => acc + x
+	const cpsFun = (cb1, cb2) => {cb1(2); cb2(3)}
+	const newCps = scan(10,11)(r, r)(cpsFun)
+	t.plan(2)
+	newCps(t.cis(10+2), t.cis(11+3))	
+})
+test('scan with multiple functions applies each to the same seed', t=>{
+	const r1=(acc, x) => acc + x, r2=(acc, x) => acc * x
+	const cpsFun = (cb1, cb2) => {cb1(2); cb2(3)}
+	const cpsFun1 = (cb1, cb2) => {cb2(2); cb1(3)}
+	const newCps = scan(10,10)(r1, r2)(cpsFun)
+	const newCps1 = scan(10,10)(r1, r2)(cpsFun1)
+	t.plan(4)
+	let count = 0
+	newCps(t.cis(10+2),t.cis(10*3))
+	count = 0
+	newCps1(t.cis(10+3),t.cis(10*2))
+})
 // test('scan throws with fewer than 2 args', t=>{
 // 	t.throws(_=>scan())
 // 	t.throws(_=>scan(1))
 // })
 
-// test('scanN implies seed=undefined', t => {
-// 	const reducer = (acc=10, x) => acc + x
-// 	const cpsFun = cb => cb(42)
-// 	t.plan(1)
-// 	scanS(reducer)(cpsFun)(t.cis(52))
-// })
-// test('scanN works with multiple args with seed=undefined implied', t => {
-// 	const r1=(acc=0, x) => acc + x, r2=(acc=1, x) => acc * x
-// 	const cpsFun = (c1,c2) => {c1(10);c2(20)}
-// 	t.plan(2)
-// 	let count = 0
-// 	scanS(r1,r2)(cpsFun)(res => t.cis(count++ === 0 ? 0+10 : (0+10)*20)(res))
-// })
+test('scanS implies seed=undefined', t => {
+	const reducer = (acc=10, x) => acc + x
+	const cpsFun = cb => cb(42)
+	t.plan(1)
+	scanS(reducer)(cpsFun)(t.cis(10+42))
+})
+test('scanS works with multiple args with seed=undefined implied', t => {
+	const r1=(acc=0, x) => acc + x, r2=(acc=1, x) => acc * x
+	const cpsFun = (c1,c2) => {c1(10);c2(20)}
+	t.plan(2)
+	scanS(r1,r2)(cpsFun)(t.cis(0+10), t.cis(1*20))
+})